kernel/trace/trace_sched_switch.c

   1 /*
   2  * trace context switch
   3  *
   4  * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
   5  *
   6  */
   7 #include <linux/module.h>
   8 #include <linux/kallsyms.h>
   9 #include <linux/uaccess.h>
  10 #include <linux/ftrace.h>
  11 #include <trace/events/sched.h>
  12
  13 #include "trace.h"
  14
  15 #define RECORD_CMDLINE  1
  16 #define RECORD_TGID     2
  17
  18 static int              sched_cmdline_ref;
  19 static int              sched_tgid_ref;
  20 static DEFINE_MUTEX(sched_register_mutex);
  21
  22 static void
  23 probe_sched_switch(void *ignore, bool preempt,
  24                    struct task_struct *prev, struct task_struct *next)
  25 {
  26         int flags;
  27
  28         flags = (RECORD_TGID * !!sched_tgid_ref) +
  29                 (RECORD_CMDLINE * !!sched_cmdline_ref);
  30
  31         if (!flags)
  32                 return;
  33         tracing_record_taskinfo_sched_switch(prev, next, flags);
  34 }
  35
  36 static void
  37 probe_sched_wakeup(void *ignore, struct task_struct *wakee)
  38 {
  39         int flags;
  40
  41         flags = (RECORD_TGID * !!sched_tgid_ref) +
  42                 (RECORD_CMDLINE * !!sched_cmdline_ref);
  43
  44         if (!flags)
  45                 return;
  46         tracing_record_taskinfo(current, flags);
  47 }
  48
  49 static int tracing_sched_register(void)
  50 {
  51         int ret;
  52
  53         ret = register_trace_sched_wakeup(probe_sched_wakeup, NULL);
  54         if (ret) {
  55                 pr_info("wakeup trace: Couldn't activate tracepoint"
  56                         " probe to kernel_sched_wakeup\n");
  57                 return ret;
  58         }
  59
  60         ret = register_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  61         if (ret) {
  62                 pr_info("wakeup trace: Couldn't activate tracepoint"
  63                         " probe to kernel_sched_wakeup_new\n");
  64                 goto fail_deprobe;
  65         }
  66
  67         ret = register_trace_sched_switch(probe_sched_switch, NULL);
  68         if (ret) {
  69                 pr_info("sched trace: Couldn't activate tracepoint"
  70                         " probe to kernel_sched_switch\n");
  71                 goto fail_deprobe_wake_new;
  72         }
  73
  74         return ret;
  75 fail_deprobe_wake_new:
  76         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  77 fail_deprobe:
  78         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  79         return ret;
  80 }
  81
  82 static void tracing_sched_unregister(void)
  83 {
  84         unregister_trace_sched_switch(probe_sched_switch, NULL);
  85         unregister_trace_sched_wakeup_new(probe_sched_wakeup, NULL);
  86         unregister_trace_sched_wakeup(probe_sched_wakeup, NULL);
  87 }
  88
  89 static void tracing_start_sched_switch(int ops)
  90 {
  91         bool sched_register = (!sched_cmdline_ref && !sched_tgid_ref);
  92         mutex_lock(&sched_register_mutex);
  93
  94         switch (ops) {
  95         case RECORD_CMDLINE:
  96                 sched_cmdline_ref++;
  97                 break;
  98
  99         case RECORD_TGID:
 100                 sched_tgid_ref++;
 101                 break;
 102         }
 103
 104         if (sched_register && (sched_cmdline_ref || sched_tgid_ref))
 105                 tracing_sched_register();
 106         mutex_unlock(&sched_register_mutex);
 107 }
 108
 109 static void tracing_stop_sched_switch(int ops)
 110 {
 111         mutex_lock(&sched_register_mutex);
 112
 113         switch (ops) {
 114         case RECORD_CMDLINE:
 115                 sched_cmdline_ref--;
 116                 break;
 117
 118         case RECORD_TGID:
 119                 sched_tgid_ref--;
 120                 break;
 121         }
 122
 123         if (!sched_cmdline_ref && !sched_tgid_ref)
 124                 tracing_sched_unregister();
 125         mutex_unlock(&sched_register_mutex);
 126 }
 127
 128 void tracing_start_cmdline_record(void)
 129 {
 130         tracing_start_sched_switch(RECORD_CMDLINE);
 131 }
 132
 133 void tracing_stop_cmdline_record(void)
 134 {
 135         tracing_stop_sched_switch(RECORD_CMDLINE);
 136 }
 137
 138 void tracing_start_tgid_record(void)
 139 {
 140         tracing_start_sched_switch(RECORD_TGID);
 141 }
 142
 143 void tracing_stop_tgid_record(void)
 144 {
 145         tracing_stop_sched_switch(RECORD_TGID);
 146 }